Nuevo Observatorio Virtual Argentino

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D18 small galaxy systems galaxies catalogue


Catalogue of small galaxy systems from SDSS-DR14


Fernanda Duplancic

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We aim at defining homogeneous selection criteria of small galaxy systems in order to build catalogues suitable to compare main properties of pairs, triplets, and groups with four or more members. To this end we use spectroscopic and photometric Sloan Digital Sky Survey data to identify systems with a low number of members. We study global properties of these systems and the properties of their member galaxies finding that galaxies in groups are systematically redder and with lower star formation activity indicators than galaxies in pairs which have a higher fraction of star-forming galaxies. Triplet galaxies present intermediate trends between pairs and groups. We also find an enhancement of star formation activity for galaxies in small systems with companions closer than 100 kpc, irrespective of the number of members. We have tested these analyses on SDSS mock catalogues derived from the Millennium simulation, finding as conservative thresholds 76 per cent completeness and a contamination of 23 per cent in small galaxy systems, when considering an extreme case of incompleteness due to fiber collisions. Nevertheless, we also found that the results obtained are not likely affected by projection effects. Our studies suggest that an extra galaxy in a system modify the properties of the member galaxies. In pairs, galaxy-galaxy interactions increase gas density and trigger starbursts. However, repeated interactions in triplets and groups can generate gas stripping, turbulence, and shocks quenching the star formation in these systems.


On the nature of small galaxy systems

Data Table Fields:

NameTable Head DescriptionUnitUCD
tile_name Tile id source tile name N/A meta.code;
Id Id System identifier N/A
idgx Idgx alaxy identifier within the system. If the system has N members then idgx range from 1 to N being idgx=1 the brightest galaxy in the system and idgx=N the faintest one N/A
Nm Nm number of members in the system N/A meta.number
objid Objid Unique SDSS identifier N/A id_main
idsp Idsp If idsp=0 the galaxy is spectroscopic and if idsp=1 it is a photometric galaxy N/A
ra Ra J2000 right ascension of the system geometric deg pos.eq.ra;meta.main
dec Dec J2000 declination of the system geometric deg pos.eq.dec;meta.main
z Z Galaxy redshift N/A src.redshift
Mr Mr r-band absolute magnitude of the galaxy mag phys.magabs
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